| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | BSk - Cold Semi-Arid Climate |
| Ecoregion: | 10b - Loess Islands |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 98850 - Rock Island, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 20 | 24 | 30 | 37 | 44 | 51 | 56 | 56 | 48 | 37 | 29 | 21 | 38 |
| Avg Max Temp (°F) | 34 | 40 | 51 | 61 | 70 | 77 | 85 | 85 | 76 | 61 | 43 | 33 | 60 |
| Avg Precip (In.) | 2.42 | 1.69 | 1.3 | .74 | .83 | .88 | .42 | .48 | .59 | 1.08 | 2.19 | 2.75 | 15.38 |